Chromium/silica catalysts can be used to make ethylene-based polymers, such as HDPE. However, the ability to manipulate or control the molecular weight, the molecular weight distribution, and the amount of long chain branching of such polymers, based solely on the physical structure of the chromium/silica catalyst, is not fully understood. It would be beneficial to modify certain physical parameters of the catalyst—such as surface area and pore volume—in order to manipulate or control important molecular weight and branching properties of the polymer. Accordingly, it is to this end that the present invention is generally directed.